Transformer



Patented Oct. 16, 1928.

UNITED STATES FRANCIS DE WILLY, LOS ANGELES, CALIFORNIA.

TRANSFORMER.

vimplication filed April 20, 1926. Serial No. 163,378.

My' invention relates to high frequency. transformers, particularly adapted, although not necessarily, for use in radio apparatus.-4

It is a purpose of my invention toI provide a transformer so wound that itsv magnetic field is con-fined to a restricted area so that in use in a radio circuit, for example, where it is 1 and novel method of Winding the secondary and in such manner that counter-magnetic fields are set up which operate to utilize that part of the primary magnetic field which ordinarily leaks beyond the secondary, thus confining the magnetic field within the area defined by the instrument itself.

ume and natural tone quality when incorporated in .a radio receiving circuit.

I will describe only one forlvv of 'transformer embodying my inventio andwill point out the novel features thereof in claims. In the drawings: Fi u're 1 is a view showing in perspective one orm of transformer embodying Aiii-'- vention; y

Figure 2 is al-plan view of the transformer shown in Figure 1. A f

. Referring specifically to the-drawings, my invention in its present embodiment comprises an inner frame or sleeve 15 disposed centrally within an outer frame 16, the two lframes beingof tubular form -in the present instance and constructed of suitable insulating material. The outer frame 16 is formed at diametrically opposed points with slots 17,

. which extend inwardly from one end of the frame and terminate in spaced relation to the other end of the frame. Within the inner frame 15 is'arranged a primary. winding 18,. while associated with .the inner and outer frames is a single lengthv of insulated Wire constituting the secondary winding of the transformer.l This wire, vone end of which is indicated at 19, is trained around .the outer side of one-half of the outer frame 16, or, in other Words, extends from one slot 17 to the other. From this point the wire is extended inwardly, as indicated'at 20, and tangentially of the inner frame 15,Whence it is extended around one side of the frame 15, vas indicated at 21, so as to encompass substantially one-half of the frame. From this point the wire lextends tangentially from the inner frame 15, as indicated at 22, and in a direction opposed to, but substantially parallel with,-the stretch 20. In continuing its Winding the Wire is trained about the outer side of the other half of the outer frame 16, as indicated at 23, so as to extend from one vslot 17 to the other, whence it extends inwardly 4of the outer frame and tangentially of the inner frame, as indicated at 24, and then around the other half of the inner frame 15, as indicated at 25. From this point the wire is extendedv tangentially from the inner frame, as indicated at 26,'thus completing what may be termed one convolution of the rwinding. The remainder of the secondary ,Winding is completed by merely repeating the l convolutions as just traced to the opposite end of the wire, as indicated at 27. v In this v manner the secondary is formed into an inner coilpindicated at C in Figurel 2, and two outer coils C', the inner coil being in inductive coils in noninductiverelation to the primary winding, as will be seen from considering the following operation.

, With current supplied to the primary `winding 18 there is'induced into the coil C a current which flows in the same direction as the'current traversing the primary wire, all

"las indicated b the arrows in Figure 2, and asga result of t is current there will be caused `to flow in the coils C a current Which is merelya continuation of the current traversing the coil C. By noting the arrowsin Fi ure 2, the course of the current through all o the coils can be readily traced, and it will be particularly noted that although the current in the coil C is flowing in the same direction as the current of the primary winding the current of the coils C flows in directions opposed to the current flow in the respective 1 adjacent portions of the primary winding.

c By reason of this the coils C set up magnetic fields whichcoppose the' magnetic field emanating lfrom theprimary winding, and because of the encircling positions of the coils C it will be manifest that the magnetic fields set up thereby will operate to neutralize the primary. magnetic field to prevent the latter from extending beyond the area defined by the instrument. Of. coursc there will be a slight leakage of the magnetic field through the slots 17 of the outer frame 16,'but'it will be understood that the frame 16 can be so designed as to render these slots relatively narrow and hence bringvthe coils C into closer proximity, thereby completely enclosing the primary magnetic field or the magnetic field of the primary.

A transformer constructed in accordance with my `invention possesses a high degree of.

selectivity through the ability to inductively couple the primary winding to only a relatively small portion of the secondary winding, namely, the coil C. The completely closed magnetic field permits the intimate association ofthe transformer with others in a radio set without the possibility of the magnetic fields of the two transformers overlapping and thus creating spray feedback or interstage coupling. It is to be particularly noted that the coils C and C are space wound, which greatly reduces the loss of magnetic energy and as a consequence likewise the high frequency resistance to a minimum.

Although I have herein shown and described only one form of -transformer embdying my invention, it is to vbe understood that various changes vand modifications may be made therein without departing from the spirit of the invention, and the4 spirit and scope of the appended claims.

I claim:

1. A- transformer comprising an inner tu- .bular frame, a primary in the frame, an outer I the fiat sides of the other coils.-

3. A transformer comprising a primary and a secondary continuously wound to form an inner coil surrounding the primary and two outer coils positioned and co-acting to substantially surround the inner coil, the secondary coils being so wound that current induced in the inner coil vWill iow in the same directionas the current in the primary, and the current in the outer coils which will flow in directions opposed to the current iow in the 'respective adjacent portions of the primary. p

4. A transformer comprising an inner frame, a primary thereon, an outer frame around the inner frame, having slots therein, and a secondary continuously wound to -form a main coil on the inner frame encircling the primary, and outer coils extending through the slots and to and around the outer side of the outer frame to substantially surround the main coil.

FRANCIS lDE WILLY. 

